Recently, frauds (what are called bank transfer fraud, “it's me” fraud, “help me, mother” fraud, and the like) for swindling money and goods by pretending to be a relative have increased. For this reason, various measures for preventing such frauds are proposed.
PTL 1 describes a technique in which voice characteristics (voiceprint or the like) of a swindler are recorded in a swindler voice database in advance, and when voice characteristics of received call voice data coincide with the voice characteristics recorded in the database, the call is determined as a call from the swindler. In addition, PTL 2 describes a technique of recording an amount of individuality characteristic of a close relative in a storage unit in advance, determining whether or not an amount of individuality characteristic of a caller coincides with the amount of individuality characteristic recorded in the storage unit, and, when determining non-coincidence, notifying a call recipient (such as an elderly person living alone) of the result.